Need Ventilation Help

Discussion in 'Grow Room Design/Setup' started by fyrhazzrd, May 7, 2011.

  1. #1 fyrhazzrd, May 7, 2011
    Last edited by a moderator: May 7, 2011
    I'm a little confused. I have a 4X4X6.5 Tent in a bedroom. I have a small desktop fan blowing 24x7 as well as a ceiling fan blowing 24x7. I have been having some serious heat problems. If I zip up the tent so that it is light proof. Temps will reach 100+ degrees. If I leave the front of the tent unzipped it will get to 85 degrees.

    So today I went out and purchased a new light hood. I purchased a 6" vented air cooled hood and a 6" 465 CFM fan. I have it all hooked up with the fan sucking air through the hood and pushing the air through the ducting and out of my bedroom window.

    Long story short my temps aren't even going down one single degree. I'm still stuck at 85 degrees. If I put my hand over the vent on the light that is open I can feel quite a bit of air sucking through it; however if I move my hand two or three inches from the hood there is nothing.

    Edit: Forgot to mention the light is a 400 Watt HPS. I have a 1000 Watt light I was going to use for flowering, but at this point I'm afraid to.

    Here is a picture of what I have.

    Attached Files:

  2. what i did was ran my exhaust to an attic space, put my fan in the attic so it wouldn't heat my grow space. make sure all electronics are outside tent. and oscillating fans are the shit also.
  3. I'm afraid if I mount the fan outside of the tent that my airflow will literally drop off to nothing. I feel like I'm next to nothing now as it is.

    My poor plant is hating this heat. It is starting to shrivel up pretty bad from the heat stress now. What do plants do that is growing outside? I know it gets hotter than 85 in the real world.
  4. my airflow chart goes like this; filter->grow room->carbon filter-> light-> ducting->fan.
    make sure you have enough intake to replace the air.
    it ain't perfect but it gets the job done for me.
    i also recommend putting the fan outside your tent, not only to keep the heat down but also to keep it semi-stealthy.
  5. #5 rhapsodyrcks, May 7, 2011
    Last edited by a moderator: May 7, 2011
    You need to get your plants outta that heat. I would suggest you take them out temp and run your tents in different configs till you get the temp right. i did that took me about 2 hours.

    I have a 32x32x62 grow tent with a 400watt HPS tube in it. What I did was

    Filter>>Duct>>Light tube>Out Light Tube>Duct going out of tent>Fan outside of tent. Duct taped and ziped tied the whole thing. I also made sure that the fan was on the side of the bulb part.

    Then I have another duct inside it pulling air out though another fan outside the tent.

    The reason why your hood has two ends is so you can run air over it.

    Its generally better to pull air then to push air as well.

    Also make your ducts as short as possible with allowing enough length to move it up and down. You would be surprised at what a difference that can make. You should raise your light to if your getting to much heat. Put a temp probe at plant level..thats where it matters. You will get less light on them but its better then baking them to a crisp.
  6. Ok; If I understand what you are saying is that I need to move the fan outside of the tent and on the other side of my light. Currently it is on the opposite side of the hood that the bulb socket is on.

    Also I should put another duct on it and run it outside the tent as well.

    Third I need a second fan to pull through my filter. I do have a filter, but when I hooked it up to my fan I had zero suction through the filter.

    Currently my light is 20" above the canopy of my single plant. It is still a very young plant 3.5 weeks from seed I think. Only about 5" tall. When I place my hand right above my plant, I don't feel any heat off of the light at all. I only feel a little warmth if I place my hand right under the light.

    I can post a picture of my poor pathetic looking plant if you like. I kind of feel sorry for it. I'm am almost 100% positive that it is heat stressed, and not malnourished.
  7. please do not clutter your thread with useless info for now with pics of your plant...

    where are you pushing your hot exhausted air too? the attic/outside or an adjacent room? and where are you getting your cool air from?

    we need more pics of your grow space layout....

    take temp readings of the rest of your house at grow level
    temp reading at intake
    temp reading at exhaust

    close the upper ports on the tent and use the lower ports to get cool air into your tent and use the hood/exhaust fan to remove the hot air

    whats the CFM rating on your inline fan?

    try this for starters...

    any pics of how the ducting is being run will help
  8. correct try to keep your socket as cool as possible.

    it is up to you if you want a dedicated cool air source for your light. if so you need another fan and hook that up with your filter. and try to get some negative pressure in the tent so no smell escapes.
  9. #9 fyrhazzrd, May 7, 2011
    Last edited by a moderator: May 7, 2011
    Ok, I went upstairs and made a few changes and took a couple pictures.

    I moved the fan outside the tent, and moved it to the lamp socket side of the hood. I attached a duct to the other side of the hood and ran that duct out of the tent. Both ducts go out to an open window.

    I also moved the light up to a height of 24" above the plant.

    Edit: The Tent is backed up right in front of the window. So the Ducting leaves those upper ports and runs straight to the back of the tent and out the window directly behind the tent.

    I haven't taken temp readings of the whole room, only plant level. I will do that tomorrow when the light is on. At the moment it is down to 76 degrees since the light is off. It is also a cool night as well so that helps.

    Attached Files:

  10. Well, 85 degrees is a lot cooler than 100 degrees firstly.

    Secondly , Does the hood have its glass in it?

    With 465cfm and no filter , that thing should be sucking hard, are the walls of your tent pulling in tight when you zip it up?

    Is the hood only warm (not hot) to the touch?

    Seems to me you have it hooked up correctly, the inline fan can be in or outside of the tent, the important part is that your pulling hot air from the hood/room and expelling it out of the area.

    What is the temp at plant level? It will always be warmer directly under the light...
  11. You had it right the first way , you need to be sucking hot air out of your room , leave the opposite side of your hood open in the room.

    Make sure your PULLING air through the hood via the room, and out the window , you may need to think about a carbon filter if it starts to stink.. depending on how close your neighbors are to your exhaust window.
  12. #12 Russy, May 7, 2011
    Last edited by a moderator: May 7, 2011
    Like a few others have said, that should create a negative pressure in your room (a good thing) make sure the room is sealed properly, and the walls should be nice and tight from the fan sucking air in through all the cracks...

    And also, its not going to give you correct reading untill you have had it zipped up for a little while, and also , your room can only be a certain coolness, your light is putting off heat , and your average house room temp is 70.

    So without any cool air coming in, your "cooling" your room via sucking your hot air hot , with 70 degree air... that should keep your temps between 80-90 (lights on temp) , thats the best you can hope for without some kind of cold air intake or A/C.
  13. I have a carbon filter. I had it hooked up at first, but there was absolutely no air being sucked through it; so I disconnected it. I will just buy a separate fan for that next week.

    My fan is pulling air through the hood, that part I did know.
  14. I think you misunderstood what I said. If the tent is zipped up the temps will climb up over a hundred degrees. Even with the new fan installed. With it unzipped it is around 85. That is the part I am worried about. It's not too much of a problem now since I'm still in veg, but when I flower, I want to be able to zip it up.
  15. honestly, 460 cfm in that small of a tent should be plenty to keep it cool, something may be wrong with your fan, or I am missing something.

    {{YOUR TENT}}

    {{{{ Filter ---> Sealed Hood--->Fan---->}}}}--> Outside

    Even with a filter, It should have been plenty to instantly create negative preassure in your tent when you turned it on and zipped it up.. does the tent stay poofy , or does it get tight from the air being pulled out !?

    You need to be pulling air out of your room (since its hot) , instead of pulling air through your hood only, thats for people that have cold air to supplement.
  16. The very first picture

    That picture looks correct to me. with the air being PULLED out and exhausted out the window. If you have it hooked up that way, and turned on full blast, and zipped up, there is no way it should get to 100 degrees with your size of light. Something would be wrong If thats the case. Your tent walls should be straining against the fan pulling hard.
  17. OK, I'll try it again tomorrow. It's getting late tonight. I'll disconnect the opposite end again, and see if the temps climb again. Should I leave the bottom air vents of the tent open, or seal those up again?

    And yes, I do have the glass installed in my vented hood.
  18. You need to get Neg pressure , seal up the passive intakes (im assuming thats what you meant) the fan will easily be able to pull air through the small cracks , zipper etc.

    My Flower room is simply a larger version of yours, I pull my air through the filter (on the floor ) , through 2 hoods, and then out of the house.


    The air is being pulled left to right , the fan is not pictures, but its the same concept as yours..


    Edit: Ignore the white ducting , its not in use, the silver ducting is like yours.
  19. Hope you can get your temps in control! Environment is everything !!

    Good luck !

  20. Thanks man, it is very frustrating, especially since I just dropped $400 on a fan and hood :cool: I would sure hate to be it all for naught. My old hood was an el cheapo open foil looking thing. I expected the air cooled to really make a difference. And everything I read online said I should have about 350 CFM for my size area. So I figured the 460CFM would be good to go.

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